Stern Ramp

What Sets a Stern Ramp Apart

A stern ramp is mounted across the transom and swings down to meet the quay, linkspan or another ship's ramp in a direct line with the vehicle deck. That straight-through geometry is the whole point: a quarter ramp is offset to one side because the berth or the ship's stern shape does not allow a straight approach, and a bow ramp or visor serves the same purpose at the opposite end of the ship, usually behind a separate weathertight bow door. Where a stern ramp forms part of the shell plating below the freeboard deck, it is not just cargo-handling gear, it is a hull closing appliance, and that changes how it is built, tested and monitored.

Main Components

• Ramp platform – stressed steel plate, often with a hinged flap or extending apron at the outboard end to bridge tidal range and quay height differences.
• Hinge and pintle arrangement – carries the ramp's weight and the vehicle loads crossing it back into the ship's structure.
• Hydraulic lifting cylinders – raise and lower the ramp; on larger ramps working in pairs with synchronising valves to keep the ramp level.
• Suspension wires or chains – found on older or lighter designs as a backup or primary lift path instead of direct cylinder connection.
• Locking devices – cleats or wedges that take the sea-going load off the hydraulics once the ramp is stowed, so the cylinders are not the only thing holding it shut.
• Hydraulic power pack and local/remote control station.
• Position indicators and interlocks – feed ramp-open/closed status to the bridge, and on some ships block propulsion or gangway use until the ramp is confirmed closed and locked.

Selection and Sizing

Sizing starts with the heaviest axle load the ramp must carry repeatedly, not the vehicle's total weight, since a concentrated axle or outrigger load governs plate thickness and stiffening. Ramp angle has to stay within the ground clearance and articulation limits of the trailers and mobile cargo actually used on the route, which is why maximum tidal range at the intended berths is checked before ramp length is fixed. Width is set by lane configuration on the deck below, and steel grade and corrosion allowance need to account for constant wetting, road salt and ballast splash rather than dry cargo-hold conditions.

Regulations and Class

Where the ramp forms part of a hull opening below the freeboard deck, SOLAS Chapter II-1 closing appliance requirements apply, including position indication at the navigating bridge and, following the ferry losses that drove the current rules, television surveillance or equivalent monitoring of the ramp seal area on many RoRo ships. Class societies require periodic operational testing and survey of the hydraulic system, locking devices and indicators, and IACS unified requirements cover the closing devices on hull openings of this kind. A ramp used purely as an internal or dry-deck access with no hull opening role is surveyed as cargo gear rather than a closing appliance, which is a lighter regime.